A project is proposed for the study of the mechanism of action of the carbon electrodes used to monitor neurotransmitters and other biological compounds. The goal of the project is the modification of carbon electrodes so that their behavior is sensitive and reproducible in the analysis of catecholamines and related compounds in biological media. The aim is to minimize the troublesome adsorption of the analyte to the electrode surface, but to keep the electrode activated for oxidation of these biogenic amines. Carbon electrodes will be employed to determine which surface functional groups facilitate efficient oxidation and which cause adsorption onto the electrode. Chemical modification of the carbon surface functional groups will be carried out to differentiate the specific surface groups which control adsorption and electrocatalysis. Using selective surface modification an optimum electrode will be developed with a reproducible redox potential, and with minimum adsorption to the surface. This modified electrode will then be tested in a laboratory simulation of the in vivo and in vitro conditions common in neurochemistry.